The collapse of cycles in the dynamics of North American grouse populations
Cyclic dynamics of bird and mammal populations are commonly reported in northern latitudes throughout the world, and recent European observations on rodents and grouse suggest that cycle periods decline towards southern latitudes. To investigate latitudinal patterns of cyclic dynamics in North Ameri...
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Published in | Ecology letters Vol. 7; no. 12; pp. 1135 - 1142 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Blackwell Science Ltd
01.12.2004
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Subjects | |
Online Access | Get full text |
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Summary: | Cyclic dynamics of bird and mammal populations are commonly reported in northern latitudes throughout the world, and recent European observations on rodents and grouse suggest that cycle periods decline towards southern latitudes. To investigate latitudinal patterns of cyclic dynamics in North America, we assembled 27 long‐term data sets collected between 1939 and 2001 for three grouse species. By fitting the data with autoregressive models to measure direct and delayed density dependence, we show that, in contrast to European studies, North American grouse exhibit period increases from north to south, with cycles collapsing via period lengthening. This occurs because delayed density dependence decreases in southern latitudes, whereas direct density dependence increases. These results show that cyclic dynamics can dissipate by period lengthening as well as the period shortening postulated for European grouse and rodents. |
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Bibliography: | ark:/67375/WNG-3M2J0SR1-4 istex:377B4D6B60BF509E3034343C2B074AF0AA8DB26E ArticleID:ELE673 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 1461-023X 1461-0248 |
DOI: | 10.1111/j.1461-0248.2004.00673.x |